Bronzing is a lustrous sheen of a printed sample in reflected light which can be associated with only certain dyes. Specifically, bronzing refers to a reddish-brown color of the ink upon drying. It is particularly an undesirable property of black inks because of lowered optical densities produced. However, it also can affect other colors, cyan producing a reddish tone, for example. Bronzing is an undesirable print quality issue for the customer and prevents color attributes from being measured.
One solution proposed is to raise the pH of the ink. However, it has been found that a pH increase of the ink is liable to cause materials degradation in the printhead by the ink.
Thus, a means of reducing, or, preferably, even eliminating, bronzing of inkjet inks printed on print media is needed.